SimpleCo (int, const char *=0)This constructor takes an integer argument which is the number of atoms needed to describe the coordinate.SimpleCo (const Ref< KeyVal > &, int natom)TheKeyVal constructor requires the number of atoms. int natoms () const Returns the number of atoms in the coordinate.int operator[] (int i) const Returns the index of the i'th atom in the coordinate.void save_data_state (StateOut &)Save the base classes (with save_data_state) and the members in the same order that theStateIn CTOR initializes them. SimpleCo (StateIn &)

The SimpleCo abstract class describes a simple internal coordinate of a molecule.

The number atoms involved can be 2, 3 or 4 and is determined by the specialization of SimpleCo.

There are three ways to specify the atoms involved in the internal coordinate. The first way is a shorthand notation, just a vector of a label followed by the atom numbers (starting at 1) is given. For example, a stretch between two atoms, 1 and 2, is given, in the ParsedKeyVal format, as

stretch<StreSimpleCo>: [ R12 1 2 ]

The other two ways to specify the atoms are more general. With them, it is possible to give parameters for the IntCoor base class (and thus give the value of the coordinate). In the first of these input formats, a vector associated with the keyword atoms gives the atom numbers. The following specification for stretch is equivalent to that above:

stretch<StreSimpleCo>:( label = R12 atoms = [ 1 2 ] )

In the second, a vector, atom_labels, is given along with a Molecule object. The atom labels are looked up in the Molecule object to find the atom numbers. The following specification for stretch is equivalent to those above:

This constructor takes an integer argument which is the number of atoms needed to describe the coordinate. A second optional char* argument is a label for the coordinate. This argument is passed on to the IntCoor constructor.